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abaf26266d
Summary: Some changes to PlainTable format: (1) support variable key length (2) use user defined slice transformer to extract prefixes (3) Run some test cases against PlainTable in db_test and table_test Test Plan: test db_test Reviewers: haobo, kailiu CC: dhruba, igor, leveldb, nkg- Differential Revision: https://reviews.facebook.net/D14457
78 lines
2.9 KiB
C++
78 lines
2.9 KiB
C++
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file. See the AUTHORS file for names of contributors.
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#pragma once
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#include <memory>
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#include <stdint.h>
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#include "rocksdb/options.h"
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#include "rocksdb/table.h"
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namespace rocksdb {
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struct Options;
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struct EnvOptions;
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using std::unique_ptr;
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class Status;
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class RandomAccessFile;
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class WritableFile;
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class Table;
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class TableBuilder;
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// IndexedTable requires fixed length key, configured as a constructor
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// parameter of the factory class. Output file format:
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// +-------------+-----------------+
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// | version | user_key_length |
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// +------------++------------------------------+ <= key1 offset
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// | [key_size] | key1 | value_size | |
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// +------------+-------------+-------------+ |
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// | value1 |
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// | |
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// +----------------------------------------+---+ <= key2 offset
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// | [key_size] | key2 | value_size | |
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// +------------+-------------+-------------+ |
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// | value2 |
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// | |
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// | ...... |
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// +-----------------+--------------------------+
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// If user_key_length = kVariableLength, it means the key is variable length,
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// there will be an extra field for key size encoded before every key.
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class PlainTableFactory: public TableFactory {
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public:
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~PlainTableFactory() {
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}
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// user_key_size is the length of the user key. If it is set to be
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// kVariableLength, then it means variable length. Otherwise, all the
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// keys need to have the fix length of this value. bloom_num_bits is
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// number of bits used for bloom filer per key. hash_table_ratio is
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// the desired utilization of the hash table used for prefix hashing.
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// hash_table_ratio = number of prefixes / #buckets in the hash table
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explicit PlainTableFactory(uint32_t user_key_len = kVariableLength,
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int bloom_num_bits = 0,
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double hash_table_ratio = 0.75) :
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user_key_len_(user_key_len), bloom_num_bits_(bloom_num_bits),
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hash_table_ratio_(hash_table_ratio) {
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}
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const char* Name() const override {
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return "PlainTable";
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}
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Status GetTableReader(const Options& options, const EnvOptions& soptions,
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unique_ptr<RandomAccessFile> && file,
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uint64_t file_size,
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unique_ptr<TableReader>* table) const override;
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TableBuilder* GetTableBuilder(const Options& options, WritableFile* file,
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CompressionType compression_type) const
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override;
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static const uint32_t kVariableLength = 0;
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private:
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uint32_t user_key_len_;
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int bloom_num_bits_;
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double hash_table_ratio_;
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};
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} // namespace rocksdb
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